Conventionally, a technique in which a plurality of cell aggregates are stacked to form a three-dimensional structure is known. In this technique, a plurality of cell aggregates that are arranged on a culture plate are picked up and pierced on each of needle-shaped bodies protruding from a support to contact each other. After the cell aggregates have fused with each other, the cell aggregates are pulled out from the needle-shaped body thereby obtaining a three-dimensional cell structure. Various techniques are known for picking up the cell aggregates arranged on a culture plate and pierce them on a needle-shaped body. Patent Document 1 discloses a technique in which a cell aggregate on a culture plate is sucked into a pipette and then transferred to a needle-shaped body, where pressure is applied to the cell aggregate for piercing the cell aggregate on the needle-shaped body, a technique in which a cell aggregate on a culture plate is held and transferred with a small-sized robot arm to be pierced on a needle-shaped body, and a technique in which a cell aggregate on a culture plate is held with tweezers to be pierced on a needle-shaped body. Patent Document 2 discloses a technique in which a cell aggregate on a culture plate is sucked on a tip of a suction nozzle that has a diameter smaller than the diameter of the cell aggregate, and pushed against a needle-shaped body until the needle-shaped body penetrates from the tip to inside of the suction nozzle, thereby piercing the cell aggregate on the needle-shaped body.